I have penetrated the castle grounds but seem to have no luck crossing a small courtyard being patrolled by one guard. I am crossing from left to right and have tried walking, creeping, and running. Getting shot each time. Oooooh.... that hurts! What is the strategy here?
Kay

The best way is to wait until the guard turns his back and look out at one of the 2 side gates. Then creep from left to right.

I presume your coming from the tree courtyard going to the right at the crate area.

Well I conquered the courtyard, now I am having another problem. Nico/Petra has just been given her security card by the guard outside the castle. Now I have to go back into the castle but I can't find a way in. I've tried the window to the wine barrels but she doesn't want to go that way. I've tried the door opposite the limo but no action there. Can't climb up the wall, no crates. How do I get back into the castle? Its raining out here and its cold. Brrrrrrr....
Kay

Behind the guard that gave you the security card are the 2 entryways - one on the left and one ion the right - that goes to the small courtyard where there is a guard that patrols back and forth.

This is the small courtyard that you as George crossed from left to right, from tree courtyard to crate area.